Most cases of toxoplasmosis in united states and other modern countries are actually spread by undercooked beef and other meats rather than from indoor cats. Toxoplasmosis is spread by oral-fecal route or from eating infected meat. It probably is not spread easily by bites or by blood contact (needle sticks). Infection with this is probably a lot more common than thought, maybe up to 50% of the human population in developed countries. Some areas, almost all of the human population is infected due to poor sanitation.
Cat saliva contains some bacteria as their normal flora that when in an -ANEROBIC- condition or deep into tissues (like a puncture wound such as a bite) can cause infection in humans and other animals. This is not really a zoonotic disease as these bacteria are very common in moist, dark environments in general (strep, staph, pasteurella, fusobacterium) Also, some cats have a zoonotic-type disease on their nails that can transmit "cat-scratch fever" (Bartonella henselae) which is usually a minor illness. Cat bites can deposit these bacteria very deep into the tissue and that's where the real issues come from. Bites are hard to clean, and topical medications cannot penetrate and this leads to severe infections.